Grafted rubber compositions are well known in the art. Poly(acrylonitrile butadiene styrene) or ABS is widely known and used as a molding and extrusion composition. In ABS, polybutadiene is grafted with acrylonitrile and styrene. For outdoor applications where the polymer composition is exposed to sunlight and weather, a saturated rubber such as polybutyl acrylate (PBA) polyethylene propylene (EP) or polyethylene propylene diene monomer (EPDM) is used in place of the butadiene used in ABS. Blends of these grafted saturated rubbers are also known.
1. Field of the Invention
The present invention is directed to a polymer composition which is a blend of (a) an olefin rubber such as ethylene propylene diene monomer rubber grafted with styrene and acrylonitrile (EPDM-g-SAN); (b) an ungrafted olefin rubber such as ethylene propylene diene monomer rubber (EPDM); (c) a poly(acrylonitrile styrene) matrix; and (d) optionally a butyl acrylate rubber grafted with styrene and acrylonitrile. These polymer compositions have a desirable balance of low gloss and impact strength which makes them especially suitable as molding and extrusion compounds for certain outdoor applications.
2. Description of Related Art
Butyl acrylate rubber and EPDM rubbers grafted with styrene and acrylonitrile are well known in the art. Such compositions are taught in U.S. Pat. No. 3,489,822 (Witt et al); U.S. Pat. No. 4,127,617 (Arrighetti et al); U.S. Pat. No. 4,145,378 (Arrighetti et al); and U.S. Pat. No. 4,912,162 (Kishida et al). Blends of a butyl acrylate rubber grafted with styrene and acrylonitrile (BA-g-SAN) and an EP or EPDM rubber grafted with styrene and acrylonitrile (EP-g-SAN or EPDM-g-SAN) are also well known and are taught in U.S. Pat. No. 4,877,826 (Beyer); U.S. Pat. No. 4,946,894 (Henton et al) and U.S. Pat. No. 5,112,895 (C. J. Chen and F. M. Peng).